The present invention relates to a trailer hitch system in which trailer balls can be exchanged easily and quickly.
Since the advent of the "horseless carriage" early in this century, vehicle owners have found it useful to pull various types of trailers behind them. Early trailers were usually connected to tow vehicle draw bars with a bolt or pin. This arrangement was noisy (due to the necessary looseness of the connection which allows for ease of turning) and often unsafe. As technology pertaining to both vehicles and roads improved in the 1930's and 1940's thus causing road speeds to increase, the need for more efficient and reliable trailer couplers became evident. As a result, the use of ball type couplers became increasingly popular and, after World War II, nearly all new light and medium duty trailers were factory outfitted with ball couplers (also referred to as ball sockets).
The trailer has proven to be a convenient and very versatile piece of equipment that can be easily adapted for a wide variety of uses with an accompanying wide range of load carrying capabilities. As a result, the need for and use of various size (and strength) ball couplers has become common. This situation has generally resulted in the use of 17/8" ball couplers for lightweight trailers, 2" ball couplers for medium weight trailers and 215/16" ball couplers on heavy weight trailers.
As the availability and widespread use of specialty consumer products such as boats, riding lawn mowers, snowmobiles and all-terrain vehicles has proliferated in recent years, so has the need for, and use of, specialty trailers to transport them. Also, technological improvements in 4-wheel-drive vehicles has made it possible to routinely pull a wide variety of trailers in both on and off-road situations. This trend has been accelerated since the mid 1980's by the availability and increasing popularity of the highly versatile "sport utility" vehicles--vehicles that afford comfort and power for highway towing while still having ample road clearance and ruggedness for off-road trailer moving.
As a result, a situation has developed where vehicle owners routinely require or encounter the need to pull a wide variety of trailers. These trailers commonly have different size ball couplers. At first glance, this would not seem to present much of a problem, since different size trailer balls can be simply bolted or unbolted to vehicle bumpers and/or hitch draw bars with commonly available wrenches. However, in the real world of rust and rocks, routine installation and removal typically becomes a time-consuming exercise of frustration. Because of safety considerations, trailer balls must be semi-permanently installed to high nut torque values, which requires heavy duty wrenches. This, in turn, results in the need for extra strong wrenches (preferably with "cheater bar" or extension bar capability) for removal. It is not uncommon in severe cases, where trailer balls have been left installed for some time (and have encountered a variety of environmental hazards), to require the aid of a cutting torch to remove the ball. Of course, this renders the ball useless for reinstallation.
Given this background, a widespread need has developed for a "quick change" ball system that permits a tow vehicle to be quickly and easily converted to different ball sizes. The ball system that meets this "quick-change" need must also meet customer demands for safety, user-friendliness and durability.